Commentary produced February 14, 2014

Below 0 F nights ending?

For the Twin Cities the count of
nights with 0 degrees F or lower temperatures stands at 44 for the
current winter season (since December 1st), the most since the winter of
1981-1982. A string of 17 consecutive days with minimum temperatures
of 0 degrees F or lower was observed from January 26 to February 11, the
8th longest such streak in the Twin Cities climate records. But this
may be the end of temperatures of 0 degrees F or below with the possible
exception of early this weekend (Fed 15). All of the forecast and
outlook models suggest more moderate temperatures for the rest of the
month. Some other counts of days with 0 degrees F or colder this winter
for other cities include:

St Cloud 52 days (most since 1981-1982)
Duluth 58 days (most since 1964-1965)
Rochester 42 days (most since 1978-1979)
International Falls 65 days (most since 2008-2009)

The
National Weather Service in Duluth reported a record string of
consecutive days with below 0 degrees F minimum temperatures, spanning
January 20 to February 11, a period of 23 days. In addition, Roland
Fowler, observer at Embarrass, MN reports that the minimum temperature
there has reached -30 degrees F or colder on 28 days so far this winter
season. This frequency of low temperatures of -30 degrees F or colder
during any given winter is exceptional in Minnesota history. There have
only been 8 historical winters that have produced at least 25 days with
daily minimum temperature readings of -30 F or colder: 1898-1899 (25
days at Pokegama Dam); 1911-1912 (25 days at Detroit Lakes); 1916-1917
(28 days at Roseau); 1921-1922 (25 days at Fort Ripley); 1935-1936 (26
days at Big Falls); 1964-1965 (25 days at Cotton); 1993-1994 (28 days at
Tower); and 1995-1996 (33 days at Embarrass).

First significant snowfall of February

For many Minnesota
climate observers the first measurable snowfalls of the month occurred
this week over February 11-13. Generally total amounts were less than 1
inch, but a few places received more, and some reported new daily record
amounts on the 13th including Duluth with 5.6 inches, Kabetogama with
5.8 inches, Cook with 5.0 inches, and Moose Lake with 4.8 inches.
Snowfall on February 13 along the north shore of Lake Superior caused
numerous traffic accidents. Some of the larger accumulations of
snowfall this week were 4.6 inches at International Falls, 5.2 inches at
Orr, 5.5 inches at Lutsen, 6.0 inches at Eveleth, 6.5 inches at Two
Harbors, and 7.5 inches at Embarrass. It looks like snowfall may be
more significant for the second half of February across the state.

Frost depths

Over the past week there were many reports of
frozen water lines in residential areas. The persistent cold has
produced deeper than normal frost penetration into the ground. Where
snow cover has been thin the ground frost has gone deeper than 40
inches. Minnesota Department of Transportation notes that under roads
and pavement some of their measurements show frost at 6 feet or deeper.
Near Ottertail, MN frost was measured at 95 inches (nearly 8 feet), and
in the Rochester area there were reports of a number of frozen water
lines this week. For many parts of Minnesota frost depth has not been
this deep since the 1970s.

Weekly weather potpourri

The Climate Research Unit at the
University of East Anglia announced earlier this month the availability
of global temperature records using Google Earth. This allows access to
the temperature records of 6000 weather stations, some of which go back
to 1850. You can find more information on this data set and how to
access it at http://www.cru.uea.ac.uk/cru/data/crutem/ge/.

States
in the Deep South, along the Mid-Atlantic seaboard, and the northeast
were impacted by a major winter storm this week. The storm brought
mixtures of rain, sleet, snow, and freezing rain which took down power
lines and brought power outages to hundreds of thousands of citizens.
Traffic accidents occurred in very high numbers, and there were
thousands of flight cancellations at major airports. Some of the states
affected included LA, FL, SC, NC, AL, GA, VA, NY, MA, CT, and PA. The
National Weather Service was given credit for accurately forecasting the
storm ahead of time to allow communities to prepare.

Following a
very wet January, more flooding rains and high winds plagued parts of
the United Kingdom this week, closing schools and railroad lines, and
causing traffic snarls. In some areas hurricane force winds accompanied
the heavy rains on Wednesday (Feb 12), and yet more heavy rains are
expected on Valentine's Day before the weekend.

MPR listener question

"When is the last time the Twin Cities has set a new daily record low
temperature reading? Has the "urban heat island" made it more difficult
to set record lows?"

Answer: The threaded Twin Cities daily
climate record goes back to 1871, so our record daily values cover a
period of over 140 years. The last time the Twin Cities registered a
new record daily minimum temperatures was 36 degrees on September 15,
2011. Since the year 2000 \, the Twin Cities have only reported 5 new
record daily low temperatures. Conversely, over the same time period,
the Twin Cities have recorded 60 new record daily maximum temperatures,
and 89 new record daily high minimum temperatures. So emphatically the
"urban heat island" effect is in play when it comes to the Twin Cities
climate record, along with climate change as well.

Side note:
With one of the coldest winters in some decades taking place this year,
other Minnesota communities, less impacted by an "urban heat island"
effect have reported several new daily record minimum temperatures.
There were 92 such reports in the month of December, 34 reports in
January, and just 2 reports so far in February. Minnesota has reported
the coldest temperature in the nation on 40 dates so far this winter.

Twin Cities Almanac for February 14th

The
average MSP high temperature for this date is 25 degrees F (plus or
minus 12 degrees F standard deviation), while the average low is 8
degrees F (plus or minus 13 degrees F standard deviation).

MSP local records for February 14th

MSP
weather records for this date include: highest daily maximum
temperature of 50 degrees F in 1882; lowest daily maximum temperature of
-5 degrees F in 1920; lowest daily minimum temperature is -25 degrees F
in 1875; highest daily minimum temperature of 33 F in 2002; record
precipitation of 0.43 inches in 1950; and a record 6.4 inches of snow
also fell on this date in 1950. Maximum snow depth on this date was 21
inches in 1979.

Average dew point for February 14th is 11 degrees
F, with a maximum of 42 degrees F in 1954 and a minimum of -33 degrees F
in 1946.

All-time state records for February 14th

The
state record high temperature for this date is 66 degrees F at Windom
(Cottonwood County) in 1954. The state record low temperature for this
date is -47 degrees F at Bagley (Clearwater County) in 1906. State
record precipitation for this date is 2.15 inches at Lynd (Lyon County)
in 1919; and state record snowfall for this date is 22.0 inches at Grand
Marais (Cook County) in 1936.

Past weather features

February
14, 1906 brought Arctic cold to northern Minnesota. Twenty communities
reported a minimum temperature of -30 degrees F or colder, while Bagley
(-47 F), Detroit Lakes (-45 F), and Bemidji (-38 F) set cold
temperature records that still stand for the date. The next day,
February 15, 1906 the temperature warmed at Bagley by 70 degrees F,
rising to an afternoon high of 23 degrees F.
On February 14, 1923
the famous "Black Dust Blizzard" came to an end in western Minnesota.
It had lasted for three days, closing schools and isolating families on
their farms. Winds of 50 mph had picked up soil in the Dakotas and
deposited this with the snow that fell across western MN counties, some
in huge drifts. At least 20 people lost their lives in this storm.

A
major winter storm crossed the state over February 13-14, 1936 bringing
5 to 10 inches of new snow to many central and northern communities.
Greatest snowfall amounts were along the north shore of Lake Superior
where Two Harbors reported 10 inches, Pigeon River reported 20 inches,
and Grand Marais reported 22 inches of new snow. February of 1936 was
the coldest in state history.
By far the warmest Valentine's Day
in state history was in 1954. Numerous daily high temperature records
were set that February 14th as most observers reported afternoon
temperatures in the 40s and 50s F. One of the few occasions when
florists could deliver unwrapped flower arrangements for Valentines in
Minnesota, that day brought even 60 degrees F to some southern
communities under bright sunny skies, and with no snow cover.

Outlook

Colder
than normal with a chance of snow on Saturday, slightly warmer and
mostly dry on Sunday. Another chance for snow, sleet, and rain with
warmer temperatures on Monday. Warming trend continues much of next
week, with another chance for mixed precipitation on Thursday.

Further information

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